Stereotactic Resection Research Articles

Stereotactic Radiosurgery Versus Microsurgical Resection for the Initial Treatment of Metastatic Cancer to the Brain

The use of Stereotactic radiosurgery for the treatment of intracranial metastases from systemic cancer has grown considerably in the last few years. Review of the literature, however, reveals a paucity of well-controlled studies to substantiate this expansion. We conducted this study to address the issue of survival after treatment with either stereotactic radiosurgery or surgical resection. Whole brain radiation was instituted in both treatment arms. This was a retrospective, case-controlled study comparing patients whose only treatment for intracranial disease was either stereotactic radio-surgery or a single surgical resection. Controlling for age, histology, whole brain radiation, tumor size, number of intracranial lesions, and pre-procedural Karnofsky performance scores, we believe this study to be the most rigorous analysis to date. Patients in the radiosurgery group survived longer (median survival = 12.5 months) than those in the surgically resected group (median survival = 8 months). Statistical analysis of these curves did not show a significant difference. Considering only length of patient survival, there is no statistical difference between stereotactic radiosurgery and microsurgical resection for the treatment of new brain metastases from systemic cancer. This conclusion is based on strict criteria as outlined in the text. A larger, prospective, randomized investigation is needed to more definitively address the issue.

Integration of functional brain mapping in image-guided neurosurgery.

Magnetoencephalographic (MEG) brain mapping was performed in 90 patients with lesions associated with eloquent sensorimotor cortex. The MEG-derived sensorimotor mapping information was utilised for risk analysis and planning. Subsequently, these patients underwent either stereotactic volumetric resection, stereotactic biopsy or non-surgical management of their lesions. In seventeen patients, the MEG sensorimotor localization was integrated into an operative stereotactic database (consisting of CT, MRI and digital angiography) to be used in an interactive fashion during computer-assisted stereotactic volumetric resection procedures. The spatial relationship between the MEG derived functional anatomy, the structural/radiological anatomy and the pathology could then be viewed simultaneously, thereby affording a safer trajectory and approach. In addition, the real-time availability of functional mapping information in an interactive fashion helped reduce surgical risk and minimise functional morbidity. All of these patients had resection of their lesions with no change in their neurological status. In conclusion, MEG is a non-invasive, accurate, and reproducible method for pre-operative assessment of patients with lesions associated with eloquent sensory and motor cortex. The interactive use of MEG functional mapping in the operating room can allow for a safer approach and resection of these eloquent cortex lesions.

CT and MRI findings after stereotactic resection of brain lesions

Objective: To describe postoperative CT and MRI findings and their time course in uncomplicated cases after stereotactic volumetric resections of brain lesions. Materials and methods: One-hundred twenty-eight imaging studies (CT, 86; MRI, 42), performed 6 h to 2 years after 52 stereotactic operations, were retrospectively reviewed and analyzed in relation to time of surgery in cases without complications. Results: The extent of resection bed did not change during the first week after operation; reduction of size then began and continued up to 3–6 months. Mass effect and edema showed no change during the first 4 days, then later regressed gradually. Pneumocephalus was found in 58% of cases in the first 3 weeks, but never later. Benign, surgically-induced enhancement appeared at the margins of encephalotomy and retractor trajectory at the end of the first postoperative week, became more prominent during the following weeks, and lasted up to 3–5 months. In the majority of cases enhancement prevented recognition of the residual tumor. Dural enhancement was observed at the craniotomy site very early after the operation and persisted up to 1 year. Meningeal enhancement over convexities was found in 44% of MRI studies. Conclusion: Extent of the resection bed, mass effect, edema, and pneumocephalus show, in uncomplicated cases, a regular regression during the postoperative period. The time course of enhancement is complex and can be a source of diagnostic misinterpretation.

Microsurgical resection of colloid cysts using a stereotactic transventricular approach

BACKGROUND Several surgical approaches have proven effective in the management of colloid cysts. Cited disadvantages of the transventricular route are its difficulty in patients with small ventricles, and the risk of postoperative seizures; advantages include the avoidance of interhemispheric retraction and venous injury, and callosal section in the transcallosal route. METHODS We retrospectively evaluated patient outcomes after minimally invasive transventricular microsurgical resection. Twenty patients underwent computed tomography-guided stereotactic resection of a colloid cyst based on trajectory planning through the middle frontal gyrus. The mean patient age was 38 years (range, 14–65 years). The colloid cyst was discovered incidentally in one patient; two patients presented in coma. Fourteen patients (70%) had preoperative hydrocephalus. RESEULTS Total or near-total (only a small remnant of cyst wall left attached to the fornix or thalamostriate vein) cyst removal was achieved in all patients. Mean follow-up after surgery was 4.3 years (range, 0.5–11 years). All patients had an excellent outcome (100%) with return to full function or employment status. Postoperative morbidity occurred in one patient (5%) who sustained a small caudate nucleus hemorrhagic contusion associated with temporary hemiparesis. A single postoperative seizure occurred in one patient 5 months after surgery; no patient developed a persistent seizure disorder. CONCLUSIONS This technique relies on the use of a precisely placed limited craniotomy, a small cortical opening (10–20 mm), a precise trajectory to the foramen of Monro, and standard microsurgical instruments. Stereotactic transventricular microsurgical resection provided safe and effective management of patients with colloid cysts, even in the absence of hydrocephalus.

Volumetric reconstruction and stereotactic computer assisted resection in intracerebral lesions.

Since 1990 112 patients have undergone stereotactic resection of intra-axial tumoural lesions with volumetric reconstruction, using the Kelly-Goerss system. Stereotactic integration of CT, angiographic and particularly MRI information, together with three-dimensional information of the lesion, provide an innovative evaluation of the most appropriate surgical approach, even for each single patient. The main limitation of this surgical method is in cases where the infiltrating part of the tumour is pre-eminent, while it can allow "macroscopically complete resection" of well circumscribed lesions, almost independently of their location and volume. Some technical aspects of stereotactic resection of brain tumours are discussed in the light of our experience.

Uncommon Brain Tumors

The widespread availability of neuroimaging tests and the increasing use of stereotactic biopsy or surgical resection to obtain a histologic diagnosis have resulted in more patients with uncommon brain tumors coming to the attention of doctors. This article reviews the presentation and management of some of the less common brain tumors in adults. These include pineal tumors, medulloblastomas, ependymomas, choroid plexus tumors, ganglion cell tumors, neurocytomas, dysembryoplastic neuroepithelial tumors, esthesioneuroblastomas, Lhermitte-Duclos disease, hemangioblastomas, chordomas, and cystic lesions.

Stereotactically-guided craniotomy for cavernous angiomas presenting wit epilepsy.

With the wider availability of magnetic resonance imaging cavernous malformations are being recognised with increasing frequency in those patients presenting with intractable epilepsy. Surgical resection is the treatment of choice. However, because these lesions are usually small and may be located in eloquent areas stereotactic resection should be considered. Stereotactically-guided resection of pathologically verified cavernous angiograms was performed in 10 patients in this series presenting with epilepsy (8 males, 2 females, mean age 32 years). Eight patients presented with medically intractable epilepsy (5 complex partial seizures, 3 grand mal seizures). Of the remaining patients one experienced multiple episodes of haemorrhage and the other headaches (with a non-diagnostic scan) both in association with epilepsy. Pre-operative localisation of the motor strip was determined in one case by functional MRI. Following resection of these lesions all patients experienced improved seizure control with a mean follow-up period of 22 months. The mean postoperative hospital stay was 5.1 days with no surgical complications recorded. We conclude that stereotactically-guided resection offers significant advantages in the management of cavernous malformations. Surgical indications for operative resection would include medically refractory epilepsy, repeated haemorrhage and those cases where there is diagnostic uncertainty.

Cavernous malformations: results of image-guided resection.

With increased use of magnetic resonance imaging (MRI), diagnosis of cavernous malformations (CMs) has become straightforward. Surgical excision is the treatment of choice for these lesions. These malformations, though, are often small and can be difficult to localize during surgery. In these cases, stereotactic resection with a frame-based system is recommended to aid in localization of the malformation. However, use of these frame-based systems can be time consuming for the surgeon and onerous for the patient. With the advent of frameless stereotactic systems, these problems can be circumvented. Therefore, stereotactic resection of 17 CMs was performed for 15 patients over the course of 2 years at our institution during an investigative trial of a frameless stereotactic device. Eight patients presented with seizures, five patients with hemorrhage, and two patients with progressive headaches. Twelve of fifteen patients had normal neurological examination results on presentation, whereas three patients had deficits resulting from intracranial hemorrhages. All patients underwent diagnostic MRI preoperatively. Fourteen lesions were found to be cortical and subcortical; the other three lesions were in the basal ganglia, lateral ventricle, and pons. Following resection, 11 of 15 patients improved. Two patients developed postoperative deficits shortly after resection. One patient with a preoperative neurological deficit remained unchanged, and one patient had a recurrence of a deficit several months following resection. Image-guided stereotactic resection provides for easy localization of small malformations without requiring the use of a stereotactic frame or retractor and is well suited for resection of cavernous malformations.

CT-guided computer-assisted stereotactic resection of brain tumours.

A computer-assisted technique was developed for CT-guided stereotactic microsurgical resection of small intracerebral lesions. An original stereotactic retractor was developed to work with the Riechert-Mundinger's equipment for precise localisation, safe exposure and microsurgical removal of these tumours. A software-program was developed to work on an ordinary IBM-compatible PC/AT. It assisted the procedure from treatment planning till the end, including tumour excision, and provided computerized support for the removal of pathological tissues within the CT-defined boundaries of the lesion. 6 patients, harbouring supratentorial intracerebral lesions underwent surgery using this technique. 2 of them suffered from brain metastases, in 1 patient a cavernous angioma was removed, 2 patients had glial tumours, and in the last patient only radiation necrotic tissue was found to be the cause of ring-enhanced lesion, which had been suspected to be a recurrent glioma. Their largest dimensions varied between 18 and 30 mm and the age of the patients ranged from 15 to 52 years. In 2 cases the lesions were localised deeply in the region of basal ganglia and thalamus. In the remaining patients the tumours were rather superficial, infiltrating subcortical white-matter close to the central sulci. There was no mortality nor significant morbidity following the procedure, the Karnofsky Performance Status (KPS) cumulative scores being either unchanged (in 3), or improved (in 3 patients). Current state and modern concepts in image-guided open stereotactic methodology is discussed.

Computer-assisted CT-guided stereotactic biopsy and brachytherapy of brain tumors.

From March 1991 to September 1993, 26 patients (aged 4-78 years) with brain tumors (4 glioblastoma multiforme, 10 nonglioblastoma multiforme, 1 mixed oligoastrocytoma, 2 carniopharyngiomas, 2 meningiomas and 7 metastases) were treated with stereotactic techniques at the Centro Internacional de Restauración Neurológica, La Habana, Cuba. A total of 28 stereotactic surgical procedures were performed with no operative mortality; they included biopsies in all cases, 1 stereotactic microsurgical resection and 12 permanent implants of 192Ir, followed by external beam fractionated radiation therapy (40-60 Gy). The present paper shows that the combined use of a stereotactic approach, a comprehensive and reliable stereotactic dosimetric planning system, stereotactic brachytherapy with 192Ir and complementary percutaneous radiation treatment constitutes a promising strategy for brain tumor management.

Stereotactic Resection of Brain Metastases in Eloquent Brain

We have treated 14-patients with metastatic tumors located in eloquent cortical areas by a stereotactic-guided keyhole craniotomy and total microsurgical excision utilizing the Pelorus stereotactic device. Patients ranged in ages from 26 to 82 years with a median age of 59 years. There were 9 women and 5 men. Ten patients presented with hemiparesis and 4 with aphasia. Primary tumor location was lung in 7, colon in 2, melanoma in 2, and breast, renal, and bone in 1 case each. Gross total resection was accomplished in all cases, with postoperative imaging confirmation of complete removal. Single metastatic tumors were removed in 12 cases, and multiple lesions in 2 cases. Twelve patients had postoperative whole brain irradiation (30 Gy/10 fractions); 2 patients had previously received whole brain irradiation, yet demonstrated tumor growth. Complete resolution of neurologic deficits was accomplished in 8 patients, 3 had improved and 2 were unchanged. One patient had resolution of preoperative deficit but developed hemiparesis secondary to a hemorrhagic infarction contralateral to the operative site. Nonneurologic morbidity includes deep venous thrombosis in 3 patients, and pneumonia in 1. Thirty-day perioperative mortality is zero, and to date no patient had died of intracranial disease. We believe that with the assistance of stereotactic localization, metastases in vital regions of the cortex can be removed with very low neurologic morbidity, and with a high proportion of patients having improvement in their level of neurologic function. The morbidity in this series compares favorably with that of stereotactic radiation series reported in the literature with local disease control and resolution of neurologic deficits that equals or exceeds stereotactic radiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Interactive intraoperative localization using an infrared-based system.

We discuss new methods of localizing and treating brain lesions for both the conventional method of a base-ring fixed to the patient's skull (referred to as frame-based procedures) and the new method of frameless procedures (no base ring). Frame-based procedures are used for finding a precise instrument position during neurosurgical procedures, such as stereotactic biopsy of deep-seated lesions, placing electrodes for functional stereotaxis or catheters with radioactive seeds for brachytherapy, or even the placement of a stereotactic retractor or endoscope for removal or internal decompression of lesions. In such procedures, the intraoperative image localization of instruments becomes useful as it tracks instruments as they travel through the preplanned trajectory. Additional intraoperative digitization of surgical instruments, e.g., bipolar suction, biopsy forceps, microscope, ultrasound probe, etc, can be achieved during the stereotactic resection of eloquent areas or deep intracranial lesions by adding an infrared-based system. Frameless procedures broaden the range of surgical approaches, image guidance planning, and operative procedures, since no ring is attached to the patient's head which might interfere with the surgical approach, and offers logistic advantages in scheduling diagnostic studies. Frameless diagnostic studies employ anatomical markers and/or surface matching techniques for data registration in the computer software surgical preplanning program. This simplifies scheduling of the procedures since the image study does not need to be acquired the same day as surgery. Frameless diagnostic studies allow for the use of more than one type of imaging data for planning and optimization of surgical procedures, and greatly improve patient tolerance and comfort during these procedures and during surgery, as compared with frame-based procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

Stereotactic and computer-assisted neurosurgery at the Cleveland Clinic: review of 501 consecutive cases.

Stereotactic and computer-assisted techniques have revolutionized the diagnosis and treatment of many disorders of the brain by directing surgical instruments, the surgeon's hands, or focused radiation to an imaged target along predefined routes. This report reviews the basic principles and techniques of stereotactic and computer-assisted procedures in 501 consecutive procedures. Procedures performed include biopsy; decompression of cysts, hematomas, ventricles, and abscesses; "point," computer-assisted volumetric, and frameless stereotactic resection of brain lesions; placement of depth electrodes; treatment of movement or pain disorders; implantation of radioactive seeds in malignant tumors; and radiosurgery. Overall, image-directed stereotactic neurosurgery proved safe, accurate, and versatile.

Computed tomography and histologic limits in glial neoplasms: tumor types and selection for volumetric resection.

Selective and accurate resection of any computed tomography (CT) or magnetic resonance imaging (MRI) defined intracranial volume is possible by employing imaging-based computer-assisted volumetric stereotactic methods. Although the target volume can be any intracranial lesion, volumetric resection techniques were most frequently applied to the most commonly referred intraaxial lesions: glial neoplasms located in eloquent brain regions. Requirements for understanding of glial neoplasms as target volumes prompted investigations of the three-dimensional spatial configuration of these lesions, their histologic margins, and the accuracy with which these margins could be detected on CT and MRI. Stereotactic serial biopsy studies have shown that glial neoplasms frequently comprise two elements: tumor tissue and isolated tumor cells which infiltrate brain parenchyma. The tumor tissue component of high grade gliomas is most accurately defined by the volume which exhibits contrast enhancement. However, tumor tissue in low grade (nonpilocytic) gliomas is usually indistinguishable from infiltrated parenchyma on CT and MRI; both are hypodense on CT and do not usually exhibit contrast enhancement. Stereotactic serial biopsy is the only reliable method by which CT hypodense tumor tissue can be differentiated from infiltrated parenchyma in low grade (nonpilocytic) astrocytomas, oligodendrogliomas, and mixed gliomas. Stereotactic volumetric resection of infiltrated parenchyma defined by CT/MRI is advisable only in nonessential brain regions. In eloquent brain areas, stereotactic resection is appropriate for the glial tumor tissue component of high grade glial neoplasms, pilocytic astrocytomas, and low grade CT hypodense gliomas in which a stereotactic serial biopsy procedure has confirmed tumor tissue only.

Resection of intraventricular tumors via a computer-assisted volumetric stereotactic approach.

Intraventricular tumors present a major challenge for neurosurgeons because of their depth and the important structures around them. Between 1984 and 1991, we performed 60 computer-assisted volumetric stereotactic resection procedures in 58 patients with intraventricular tumors (30 patients with third ventricular tumors and 28 patients with lateral ventricular tumors). The pathological findings of the tumors were as follows: colloid cyst in 27, giant cell astrocytoma in 5, central neurocytoma in 4, pilocytic astrocytoma in 4, meningioma in 3, subependymoma in 3, metastatic tumor in 3, oligodendroglioma in 2, ependymoma in 2, and miscellaneous tumors in 5 patients. Most presenting symptoms were nonlocalized--headache or cognitive dysfunction. All third ventricular tumors were approached via a frontal trajectory, and lateral ventricular tumors were approached according to the site and shape of the lesion. Total resection was achieved in 55 procedures. Overall outcome was excellent in 45 cases, good (some deficit but independent) in 5, and poor (dependent) in 3 (memory impairment, 2 patients; visual field cut, 1 patient). Two patients (3.4%) died postoperatively (one had a postoperative thalamic hemorrhage and pulmonary embolus; one had a subdural hygroma). In follow-up, three patients died from the extension of a malignant tumor or from primary cancer. Permanent morbidity was seen in three cases (5%). The authors believe computer-assisted volumetric stereotaxis is useful in removing intraventricular tumors. This technique allows us to find a safe trajectory and to locate and separate the tumor margin from the surrounding vital structures.

Operative strategy in patients with MRI-identified dual pathology and temporal lobe epilepsy

We performed a prospective study using preoperative magnetic resonance imaging to identify hippocampal formation atrophy in 15 consecutive patients with intractable partial epilepsy who had undergone a stereotactic resection of an extrahippocampal temporal lobe foreign-tissue lesion. A stereotactic lesionectomy was performed in all patients, i.e., only the imaging-defined lesion itself was resected. Hippocampal formation atrophy was identified in three of the 15 patients. Neuroimaging-detected hippocampal formation atrophy has been shown to be a reliable marker of moderate to severe mesial temporal sclerosis. All patients with hippocampal formation atrophy had an unfavorable operative outcome. Pathological examination of the hippocampus in one patient with neuroimaging-identified hippocampal formation atrophy who subsequently received an anterior temporal lobectomy revealed mesial temporal sclerosis. Nine of the 12 patients without hippocampal formation atrophy experienced a significant reduction in seizure tendency after lesionectomy. The surgically excised hippocampus in one patient without hippocampal formation atrophy who later underwent a temporal lobectomy showed no significant neuronal loss. Results of this study have modified the surgical approach taken at this institution in patients with temporal lesional epilepsy. Patients with magnetic resonance imaging-defined dual pathology now undergo a temporal lobectomy which includes resection of the hippocampus and the foreign-tissue lesion.

Stereotactic Microsurgical Resection of Cerebral Lesions

We describe our experience with stereotactic microsurgical resection of 27 lesions using the Leksell frame in 23 patients; 7 had cerebral metastases, 6 had gliomas, 6 had vascular malformations, 3 had meningiomas and 1 had radiation necrosis. Gross total removal of the lesion was accomplished in every case. All lesions were between 1.0 and 3.5 cm in greatest diameter and located either deep within the cerebral (n = 7) or superficially in areas of functional cortex (n = 20). There was no operative mortality and only minimal morbidity. Average length of operating time including frame application, imaging and resection was 4.4 h and most patients were discharged on the second postoperative day. The indications, advantages and limitations of stereotactic craniotomy are discussed and technical modifications that extend the usefulness and safety of this technique are described.

A Simple System for Stereotactic Volumetrie Resection

Stereotactic volumetric resection of deep-seated intracerebral lesions is generally believed to require expensive and complex facilities. The authors report a simple system for stereotactic craniotomy, in which the software in the computed tomographic scanner and a personal computer are used for preoperative planning and intraoperative orientation.

Stereotactic resection and its limitations in glial neoplasms.

With imaging-based volumetric stereotactic techniques, it is possible to selectively and accurately remove any CT- or MRI-defined part or all of any intra-axial neoplasm. However, glial neoplasms are composed of two elements: tumor tissue and isolated tumor cells which infiltrate brain parenchyma. In high-grade gliomas and pilocytic astrocytomas, the tumor tissue component is most accurately defined by the volume of contrast enhancement. Tumor tissue in low-grade nonpilocytic gliomas is indistinguishable on imaging from infiltrated parenchyma. Stereotactic biopsy is presently the only method by which CT hypodense tumor tissue can be differentiated from infiltrated parenchyma, which is also hypodense. In eloquent brain areas, stereotactic resection is appropriate for the tumor tissue component only in patients harboring glial tumors.

Volumetric stereotactic resection of superficial and deep seated intraaxial brain lesions.

From 1984 to 1989 a total of 374 computer-assisted stereotactic resections based on computed tomography or magnetic resonance imaging were performed on 337 supratentorial and 37 infratentorial brain lesions. Computer-assisted stereotactic volumetric resection allows a more aggressive extirpation of tumours with less damaging of the adjacent brain tissue. This procedure is of most benefit in deep seated circumscribed lesions and of less benefit in infiltrating tumours such as high grade gliomas and in fibrillary astrocytomas located in essential brain areas.